This invention relates to a linear seat recliner and, in particular, to a manually-operated latch mechanism for retaining a reclinable back of a vehicle seat in a desired position.
U.S. Pat. No. 4,245,866, issued Jan. 20, 1981, discloses a latch mechanism having a pair of toothed latches which are manually operated to engage/disengage, respectively, with teeth on opposite faces of a slidable link pivotally connected at its opposite ends to a vehicle seat and a seat back, the seat portions being joined and supported for rotation by a pivot pin and the teeth providing stepped changes in adjusted angular position. While suitable for the purposes intended, demands of the automobile industry require improvement of such latch mechanisms to render them more positive, more accessible, lighter and less expensive.
Oftentimes, depending on the seat structure, locking at opposite lateral sides of the seat would be desirable. In a bench seat tremendous torques can be placed on the latch mechanism when reclining pressure is placed on the seat back. Spaced latch mechanisms would allow the seat frame to form part of a latch frame and reduce the seat frame dimensions without impairing load carrying ability. In such locking the latch mechanisms should be synchronized to lock positively and provide an adjustability characterized in that when one side is adjusted to its desired location, the other side, will be free floating to fit in ratchet-like fashion to the next tooth that is leading or lagging. Because of a desire for simple structure, the structure should be manually operable.
In an adjustable seat structure, a back section is pivoted to a seat section and a tilt-adjusting mechanism for controlling rotation of the back to a reclining position relative to the seat. In accordance with this invention, the tilt-adjusting mechanism is characterized by an elongated rod having opposite end portions and teeth on only one face thereof, one end portion of the rod being connectable to the back at a pivot point spaced from the axis of rotation, and a latch mechanism connected to said seat for latching the rod, the latch mechanism supporting the other end portion of the rod for reciprocating movement relative to the mechanism. The latch mechanism includes first bias means for biasing the rod into a first direction to direct the seat back into an upright position, a pawl having a tooth engageable with the teeth on the rod to retain the back at a desired tilt, release means to release the pawl from engagement, including a manual operator responsive to manual pressure, a cam plate driven in response to said operator, and a pin captivated within a cam slot, one and the other of the pin and the slot, respectively, being associated with the pawl and the cam plate and second bias means for biasing the cam plate, whereby the pawl is driven into engagement with the rod.
In a further embodiment in accordance with this invention, a pivot rod extends between a master and a slave latch mechanism and the manual operator controls rotation of the pivot rod, each latch mechanism being operated by the manual operator at only one side of the seat. In this embodiment the pivot rod simultaneously drives the cam plate in the master and a lever plate in the slave, the lever plate being driven against its cam plate.
Operation of the manual operator in a release direction overcomes the second bias means whereby the pivot rod directly drives, respectively, the master cam plate against its associated pawl and the slave lever plate against its cam plate and associated pawl, simultaneously releasing the pawls from engagement with their seat adjustment rods. Release of pressure on the operator directly drives, respectively, the master cam plate and slave lever plate back to their original position, the master cam plate driving its pawl back into engagement with its rod. The second bias means in the slave drives the cam plate therein towards the lever plate whereby the slave pawl is driven back into engagement with its respective rod. If the seat has been pivoted, the first bias means drive the rods back to their first position representing the seat up position. Importantly, direct movement of the operator in the engaging direction assures that once the master pawl has gripped its rod, the free-floating slave pawl will also grip its rod, engaging with the first adjacent tooth.
Advantageously, such a tilt-adjusting mechanism permits a conventional seat frame support to be simplified and made less "robust" as the recliner mechanism provides part of the support.
Provision of a floating or slave drive plate assures that positive synchronized locking will be achieved in operation.
A further advantage of a two-sided tilt-adjusting mechanism is that straight line loading, as opposed to offset loading in the mechanism is achieved, thereby requiring less strength in the unit.
Because of the general commonality of parts found in the master and slave units, the number of different parts is reduced, thus less expensive.
Further, because of a similarity of structure in the latch mechanism, the drive shaft may be made of any desired length to permit use on seats having different widths.